臺灣博碩士論文加值系統

本文討論了FC-31戰鬥機的空氣動力學性能。這項研究的目的是探討第5代戰鬥機的空氣動力性能。它不僅適用於當前的發展，而且還適用於將來增加戰鬥機機翼配置或氣動設計的參考數據。
由於計算機技術的飛速發展，計算流體力學 (CFD) 是當今分析流體和空氣動力學問題的常用技術。與過去幾十年相比，有更多的研究與利用CFD 計算或模擬飛機的空氣動力學性能有關。它也佔近年來飛機發展的一定比例。 CFD還可以通過降低硬體與能源的成本來降低風洞測試和測試飛行的成本。同時，計算流體力學的結果有著一定的精確度和可靠性。它由離散化的程度和計算時間決定。
本研究的目標外型是中國大陸的第五代戰鬥機FC-31 (J-31)。由於沒有FC-31的確切數據和幾何形狀，因此本文將其稱為類似FC-31的配置。本研究中還有一個額外的機翼配置，用於六代戰鬥機的概念:未來戰鬥航空系統 (FCAS)。我們希望經由比較兩代戰鬥機的兩種機翼配置，將能對下一代戰機的機翼配置與氣動力設計的未來發展有所貢獻。

This thesis discusses the aerodynamic performance of the fighter, FC-31. The purpose of this study is to investigate the difference in aerodynamic performance of 5th generation of fighter. It is not only for the current development but also for increasing the reference data of the fighter configuration design in the future.
Due to the rapid development of computer technology, CFD is a common technique for analyzing fluid and aerodynamic problems now. Compared with the past few decades, there are more studies related to the use of CFD to calculate or simulate the aerodynamic performance of aircraft. It also accounts for a certain proportion of the aircraft developing in recent years. CFD can also cost down the wind tunnel testing and testing flight by decreasing the cost hardware and energy. At the same time, the results of CFD are quite precise and reliable. It is decided by the discretization level and calculation time.
The target object is FC-31 (J-31), the 5th generation of fighter of Mainland China. However, there is no exact data and geometric shape of FC-31. Therefore, it will be called FC-31-like configuration in this thesis. There is an additional configuration in this study, Future Combat Air System (FCAS), which is used for the concept of 6th generation fighter. We hope that by comparing the two wing configurations of the two generations of fighters, we will be able to contribute to the future development of the wing configuration and aerodynamic design of the next generation of fighters.

Contents
Contents I
List of Figures II
List of Abbreviations XI
List of Symbols XII
Chapter 1 Introduction 1
1.1 Research Background 1
1.2 Research Purpose 5
1.3 Research Method 6
1.4 Research Tools 6
Chapter 2 Literature Review 8
2.1 CFD Development of the Application in Fighters 8
2.2 CFD of Different Configurations 11
2.3 Wing Configuration Selection 25
2.4 Similar Studies 28
Chapter 3 Numerical Modeling 33
3.1 Governing Equations 33
3.2 Solver 34
3.3 Other Physical Quantities 34
3.4 Geometry 36
3.5 Mesh 46
3.6 Physical Settings and Numerical Solutions 54
Chapter 4 Results and Discussion 60
4.1 Results 60
4.2 Discussion 77
Chapter 5 Conclusions 97
References 100

 
List of Figures
Figure 1 (a) F-16 and [1] (b) F-CK-1 (IDF) [2] 1
Figure 2 Mirage 2000-5 [3] 1
Figure 3 (a) F-16 [5] and (b) F-35 [6] 2
Figure 4 Photograph of FC-31 [7] 3
Figure 5 Photograph of F-35 [8] 3
Figure 6 The Tempest of FCAS concept [9] 4
Figure 7 The procedure of CFD 7
Figure 8 Grid of the potential code from the paper [10] 8
Figure 9 Geometry of slender delta wing [13] 11
Figure 10 3-D grid of slender delta wing [13] 11
Figure 11 Isosurface of x vorticity coloured by pressure coefficient showing primary vortex shear layer and normal shock shape [13] 12
Figure 12 DLR-F17E configuration suspended in the wind tunnel [14] 13
Figure 13 Dimension of DLR-F17E [14] 13
Figure 14 Grid distribution around the leading-edge [14] 13
Figure 15 Comparison of CFD versus wind tunnel tests [14] 14
Figure 16 Compound delta wing geometry [16] 15
Figure 17 Computational grid and surface mesh over upper surface [16] 15
Figure 18 Pressure coefficient contour of upper surface at M = 0.85 [16] 16
Figure 19 Mach number contour of upper surface at M = 0.85 [16] 16
Figure 20 CL to AoA at different Mach numbers [16] 16
Figure 21 The position of pressure sensor device on F-16XL-1 [18] 17
Figure 22 Details of requested complete pressure instrumentation suite and layout on airplane [18] 18
Figure 23 The grid on the surface of F-16XL-1 [18] 18
Figure 24 Predicted and measured flight Cp distribution on F-16XL-1 airplane at α=5.5°, M∞=0.52 [18] 19
Figure 25 Pressure contour over the upper surface by CFD [18] 19
Figure 26 Grid on upper and lower surface [19] 20
Figure 27 Grid on the symmetry plane [19] 20
Figure 28 Pressure coefficient contour over the upper surface [19] 21
Figure 29 Pressure coefficient contour at different cross-sections along the body [19] 21
Figure 30 The evolution of the cranked kite wing [20] 22
Figure 31 The real products of the kite wing and cranked kite wing [21] 23
Figure 32 Computational grid in the region wing [22] 23
Figure 33 Pressure coefficient contours on upper surface with vortices axis and flow ribbons for free stream [22] 24
Figure 34 Schematic diagram of FCAS [23] 25
Figure 35 The 6th generation fighter at the 2019 Paris Air Show [24] 26
Figure 36 Loyal Wingman, Boeing [25] 26
Figure 37 Geometric shape of F-35 [26] 28
Figure 38 F-35 geometry in CATIA [26] 28
Figure 39 Grid of (a) computational domain, (b) upper surface and (c) lower surface [26] 29
Figure 40 (a) CL and (b) CD of different Mach number [26] 29
Figure 41 CL/CD (L/D) to AoA at different Mach numbers [26] 29
Figure 42 F-16 (a) geometry in CATIA [27] and (b) actual photo [28] 30
Figure 43 (a) CL and (b) CD of F-16 [27] 31
Figure 44 (a) Lift to drag ratio and (b) Cm of F-16 [27] 31
Figure 45 Geometric layout of ONERA M6 wing [31] 37
Figure 46 ONERA M6 wing (a) 3D geometry (b) in wind tunnel [32] 37
Figure 47 Computational domain and the position of target 38
Figure 48 The airfoil of main wing: NACA 64-206 39
Figure 49 The airfoil of control surface 39
Figure 50 (a) Photo of FC-31 [34] (b) 3-D geometry 39
Figure 51 Three view of FC-31-like configuration 40
Figure 52 (a) Top-view of FC-31 (b) Exact area to calculate MAC 40
Figure 53 (a) FC-31-like geometry with full computational domain and (b) position in the computational domain 41
Figure 54 Three view of FCAS configuration 43
Figure 55 (a) Top-view of FCAS (b) Exact area to calculate MAC 43
Figure 56 (a) Full computational domain of FCAS and (b) position of FCAS in computational domain 44
Figure 57 Full computational domain with mesh 46
Figure 58 Surface grid of ONERA M6 wing 46
Figure 59 Mesh on symmetry plane of ONERA M6 wing 47
Figure 60 Hybrid grid of ONERA M6 wing 47
Figure 61 Full computational domain with mesh 48
Figure 62 Grid convergence of FC-31-like configuration 48
Figure 63 Mesh on symmetry plane of FC-31-like configuration 49
Figure 64 Surface grid of FC-31-like configuration 50
Figure 65 Hybrid grid of FC-31-like configuration 50
Figure 66 Mesh of full computational domain 51
Figure 67 Grid convergence of FCAS configuration 51
Figure 68 Mesh on symmetry plane of FCAS configuration 52
Figure 69 Surface grid of FCAS configuration 52
Figure 70 Surface grid on the wing of FCAS configuration 53
Figure 71 Highly discretized leading-edge 53
Figure 72 Symmetry plane of ONERA M6 wing domain 54
Figure 73 Symmetry plane of FC-31-like configuration domain 56
Figure 74 Symmetry plane of FCAS configuration domain 58
Figure 75 The pressure coefficient at (a) 0.2 b and (b) 0.44 b 61
Figure 76 The pressure coefficient at (a) 0.65b and (b) 0.8b 61
Figure 77 The pressure coefficient at (a) 0.9 b and (b) 0.95 b 62
Figure 78 The pressure coefficient at 0.99 b 62
Figure 79 Cp distribution on the wing surface 63
Figure 80 Convergence of CL and CD at (a) 0° and (b) 5° angle of attack 64
Figure 81 Convergence of CL and CD at (a) 10° and (b) 15° angle of attack 64
Figure 82 Convergence of CL and CD at (a) 20° and (b) 25° angle of attack 65
Figure 83 Convergence of CL and CD at (a) 30° and (b) 35° angle of attack 65
Figure 84 Keep calculating the 0°AoA case till convergence criterion less than 10-4 66
Figure 85 Coefficients to AoA of FC-31-like configuration at 0.8 M 67
Figure 86 Lift to drag at 0.8 M 67
Figure 87 Convergence of CL and CD at (a) 0° and (b) 5° angle of attack 69
Figure 88 Convergence of CL and CD at (a) 10° and (b) 15° angle of attack 69
Figure 89 Convergence of CL and CD at (a) 20° and (b) 25° angle of attack 70
Figure 90 Convergence of CL and CD at (a) 30° and (b)35° angle of attack 70
Figure 91 Coefficients to AoA of FC-31-like configuration at 1.4 M 71
Figure 92 Lift to drag at 1.4 M 71
Figure 93 Convergence of CL and CD at (a) 0° and (b) 5° angle of attack 73
Figure 94 Convergence of CL and CD at (a) 10° and (b) 15° angle of attack 73
Figure 95 Convergence of CL and CD at (a) 20° and (b) 25° angle of attack 74
Figure 96 Convergence of CL and CD at (a) 30° and (b) 35° angle of attack 74
Figure 97 CL, CD and Cm of FCAS configuration at different AoA 75
Figure 98 Lift to drag of FCAS configuration at 0.8 M 75
Figure 99 Set different boundary conditions at the red plane of FC-31-like configuration 77
Figure 100 Set different boundary conditions at the red plane of FCAS configuration 78
Figure 101 (a) CL and (b) CD of FC-31-like configuration for different BC at engine inlet 78
Figure 102 (a) Cm and (b) L/D of FC-31-like configuration for different BC at engine inlet 79
Figure 103 (a) CL and (b) CD of FCAS configuration for different BC at engine inlet 81
Figure 104 (a) Cm and (b) L/D of FCAS configuration for different BC at engine inlet 81
Figure 105 (a) CL and (b) CD of two configurations 83
Figure 106 (a) Cm and (b) L/D of two configurations 83
Figure 107 Pressure contour on upper surface (a) 0° and (b) 5° 84
Figure 108 Pressure contour on upper surface (a) 10° and (b) 15° 85
Figure 109 Pressure contour on upper surface (a) 20° and (b) 25° 85
Figure 110 Pressure contour on upper surface (a) 30° and (b) 35° 86
Figure 111 Position of cross-section 86
Figure 112 (a) Cp distribution and (b) pressure contour at the cross-section 87
Figure 113 (a) Velocity magnitude and (b) temperature at the cross-section 87
Figure 114 Vorticity magnitude at 5° angle of attack for (a) FC-31-like and (b) FCAS configuration 88
Figure 115 Vorticity magnitude at 20° angle of attack for (a) FC-31-like and (b) FCAS configuration 88
Figure 116 Vorticity magnitude at 35° angle of attack for (a) FC-31-like and (b) FCAS configuration 89
Figure 117 Turbulence intensity at 5° angle of attack for (a) FC-31-like and (b) FCAS configuration 89
Figure 118 Turbulence intensity at 20° angle of attack for (a) FC-31-like and (b) FCAS configuration 90
Figure 119 Turbulence intensity at 35° angle of attack for (a) FC-31-like and (b) FCAS configuration 90
Figure 120 Q-criterion at 20° AoA of (a) FC-31-like and (b) FCAS configuration for a certain tolerance level 91
Figure 121 (a) CL and (b) CD of FC-31-like configuration at 0.8 & 1.4 M 92
Figure 122 (a) Cm and (b) L/D of FC-31-like configuration at 0.8 & 1.4 M 92
Figure 123 Pressure contour on upper surface at 1.4 and 0.8 M for AoA (a) 0° and (b) 5° 93
Figure 124 Pressure contour on upper surface at 1.4 and 0.8 M for AoA (a) 10° and (b) 15° 93
Figure 125 Pressure contour on upper surface at 1.4 and 0.8 M for AoA (a) 20° and (b) 25° 94
Figure 126 Pressure contour on upper surface at 1.4 and 0.8 M for AoA (a) 30° and (b) 35° 94
Figure 127 Cross-sections on FC-31-like configuration at supersonic for 20° angle of attack 95
Figure 128 Pressure contour at (a) cross-section 1 (C-S 1) and (b) 2 (C-S 2) 95
Figure 129 Pressure contour at cross-section 3 (C-S 3) 96
Figure 130 Q-criterion at 20° AoA of (a) M = 1.4 and (b) M = 0.8 for certain tolerance level 96
 
List of Tables
Table 1 F-35 wind tunnel testing hours [12] 9
Table 2 ONERA M6 wing geometry 36
Table 3 Geometry of computational domain 38
Table 4 Geometry of FC-31 41
Table 5 Geometry of computational domain 42
Table 6 Geometry of FCAS configuration 44
Table 7 Geometry of computational domain 44
Table 8 Data of grid convergence 49
Table 9 Physical settings of ONERA M6 wing 54
Table 10 Boundary conditions of ONERA M6 wing 55
Table 11 Physical setting of FC-31-like configuration 57
Table 12 Boundary condition of FC-31-like configuration 57
Table 13 Physical setting of FCAS configuration 58
Table 14 Boundary condition of FCAS configuration 59
Table 15 Forms of results 60
Table 16 Cases of comparison 77

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